Comedo naevus of the palm—a sweat duct naevus?

Abstract

A 9-year-old boy is described with keratotic pits on the left palm, present since birth, which clinically resembled those seen in comedo naevus. Histology and scanning electron microscopy of skin surface replicas showed the lesions to be large, abnormal sweat ducts. It is suggested that comedo naevi are not necessarily pilosebaceous in origin and that in our case the term sweat duct naevus may be more appropriate.

Eccrine Nevus with Epidermal Changes

“…A few cases show a variety of malformations of the ec crine apparatus as reported by Herzberg [5], Pippione et al [10], Hiro.se and Goto [6], Challa and Jona [2], Marsden et al [8], and Abell and Read [1], The eccrine nevus de scribed in this paper is of interest because of its rarity and intrication within the epider mal tissue.…”

“…Similar findings have been reported in: porokeratotic eccrine ostial and dermal duct nevus [1], comedo nevus of the palm -a sweat duct ne vus? [8] and hydrotic ectodermal dysplasia with eccrine poromatosis [12].…”

“…The malformed structures described in eccrine nevus are various: contortion of the duct [7]; diamond-shaped duct [7]; a branching off of the duct [5]; pseudobasaloid cell nest [10]; adenoid structure [10]; syringomatous picture [6]; the presence of a tubu lar structure inside the nerve sheath [2]; duc tal cell resembling the clear cells lining the eccrine secretory coils [2]; dilated sweat pore [1,8], and hyperplasia of the duct [1,8], Moreover, relying on the occurrence of the adenomatous change in the eccrine duct in our case, one may point out that the ec crine nevus with its malformed eccrine ap paratus is prone to give rise to various types of the eccrine tumors.…”

Eccrine-Pilar Angiomatous Nevus

“…In the case described by Blanchard et al [14] the comedo was accompanied by a proliferation of eccrine ductal and secretory structures in the dermis. In the case of Marsden et al [15] the clinical aspect of comedos on the palm was accompanied by dilation and hyperpla sia of the sweat duct in the superficial der mis and in the epidermis. Anomalies of the eccrine duct can also give rise to the presence of porokeratoticcornoid lamellae [16] close ly related to the intraepidermal ductal por tion and to the acrosiringium.…”

Nevus comedonicus

“…It is also consistent with the occurrence of NC in association with other mesodermal defects (see below). However, it has been alternatively proposed that palmar lesions are derived from abnormal sweat ducts [26]. It has also been suggested that NC is a variant of epidermal nevus involving the hair follicle [27, 28].…”